Mobile telephony terminal devices such as, for example, mobile telephones, are normally operated with SIM cards that are inserted interchangeably into the mobile telephony terminal devices. The SIM cards contain especially the identity of the user and serve to identify the user in a mobile telephony network and to check his/her authorization to use services of the mobile telephony network. As a rule, a SIM card is issued by the operator of the home network of a user, with whom the user has entered into a mobile telephony contract. Within the home network, the user is also listed in a register (HLR—Home Location Register). During so-called roaming, when the users sign in to a mobile telephony network they are visiting, i.e. into a mobile telephony network different from their home network, the register of the home network is likewise accessed so that the identity and authorization of the user can be checked.
In mobile telephony systems, it is common practice to regularly check the service quality. Of special interest here is the service quality when the services of the home network are used. In this process, the service quality in various mobile telephony networks is compared to each other. Such comparative tests call for the use of several SIM cards that have been issued by the operators of the mobile telephony networks that are to be compared. Moreover, the service quality that is provided in a certain mobile telephony network during roaming connections is often of interest, that is to say, when this mobile telephony network is used as the visited mobile telephony network. In order to check the service quality for users of different home networks, it is necessary to use the SIM cards that were issued by the operators of these home networks at the time of the signing in.
European patent application EP 1 094 678 A1 discloses a method for measuring the quality of roaming connections and an arrangement for carrying out the method. This known method uses at least two test stations to generate test calls via the mobile telephony network and/or to receive calls from the mobile telephony network. The data of the SIM cards needed to carry out the test calls is transmitted from a SIM card server device to the test stations. The service device is suited for accommodating a plurality of SIM cards. The infrastructure that is needed to carry out the known method is relatively complex.